1. Field of Invention
The invention relates to an intervertebral implant, especially to an artificial intervertebral disk of the introductory portion of claim 1.
2. Description of Related Art
After a damaged, natural intervertebral disk or a damaged Nucleus pulposus of an intervertebral disk is removed, implants or prostheses are introduced at the present time into the intervertebral space between two adjacent vertebrae. The objective of implanting such implants is to bring about natural conditions once again as far as possible, that is, to restore, in particular, the original intervertebral disk height and, with that, the original distance between the two adjacent vertebrae. Furthermore, it shall be possible to carry out movements of the adjacent vertebrae relative to one another in a natural way as far as possible without hindrance. For this purpose, it is essential to maintain movement possibilities while bending forwards or backwards, that is, during flexion and extension of the vertebrae, as well as during a lateral bending of the vertebrae within the natural limits. The natural ligaments and muscles along the spinal column essentially are left intact, so that these further stabilize the movements of a mechanical replacement for an intervertebral disk.
Such an intervertebral implant is known from the DE 203 20 454 of MEISEL. This known implant comprises two cover plates, lying in contact with the bones, and a joint, which is disposed between the cover plates. This joint consists essentially of a spherically shaped first joint part and of a complementary joint shell as a second joint part, so that the cover plates can be swiveled polyaxially relative to one another. It is a disadvantage of this known intervertebral implant that it is opaque to x-rays and, accordingly, no longer permits adjacent vertebrae to be observed after an implantation.